This invention relates to flexible thermoplastic bags or containers of the type having two flexible opposed sidewalls and, particularly, having fastener elements connected to the sidewalls of the container adjacent an open end of the container. More particularly, this invention relates to reclosable flexible thermoplastic bags or containers which feature an impressed pattern on the sidewalls of the bags or containers and preferably contain reclosable fasteners particularly an interlocking closure mechanism operable for being interlocked continuously over a predetermined length such as interlocking closure profiles.
It is well known in the industry to produce plastic bags or containers which feature reclosable fasteners of the type comprising interlocking closure profiles that are pressed together or pulled apart to seal or open the container. Several issued United States patents deal with processes and apparatuses for making reclosable plastic bags or containers. Representative of these patents, and of those dealing more specifically with closure mechanisms, are U.S. Pat. Nos. 4,186,786, 4,484,352, 4,755,248, 4,428,788, 4,419,159, Re. 28,969, 4,263,079, and 4,279,677. More particularly, a popular construction of a plastic bag and flexible fastener incorporates a pressure closable reopenable zipper type fastener comprising rib and groove elements.
The reclosable zipper type plastic bags generally are formed of flexible thin plastic film with front and back sidewalls with the sidewalls attached to each other along their sides seams and along a bottom edge. Adjacent the top edge and extending fully across opposed confronting inner surfaces of the mouth of the bag are a pair of cooperatively interlocking fastener strip profiles formed with respective engageable rib and groove elements made of extruded plastic material. Examples of such bags and means of manufacture thereof are disclosed in U.S. Pat. Nos. 3,198,228, 3,291,177, 3,338,284 and 3,340,116.
The reclosable zipper type plastic bags may be produced by having the zipper type rib and groove elements integrally produced with the bags or by first producing the zipper type elements as separate fastener strips which are subsequently attached to the top of the bags. In either instance, the zipper lock rib and groove elements normally are extruded and are interlocked during manufacture for convenience of storage and handling. The rib and groove elements then must be separated for filling or for use. Typically, there are flange members extending above the rib and groove elements which flange members are gripped and pulled apart to separate the rib and groove for access to the interior of the bag.
Generally, the reclosable plastic bag is made from a clear, smooth thermoplastic film web or sheet typically of a polyethylene resin material. Thus, the resulting bag product is generally a clear plastic bag having smooth sidewalls. The process of manufacturing thermoplastic bags or containers typically involves supplying a continuous web of the thermoplastic material which has been folded upon itself to form two plies. In forming individual bags, portions of the thermoplastic material are severed from the web. These severed areas become the side seams for the bags and are typically sealed at the same time as they are severed by the use of a heated wire element. Generally, the industry utilizes an extrusion die in which a closure profile of a thermoplastic resin is extruded and subsequently joined to the thermoplastic film web or sheet. Alternatively, the closure profile elements and sheet may be extruded as an integral unit from a single die whereupon the closure profile elements and sheet fuse to form an integral plastic container stock material.
Reclosable plastic bags of the general type described above have been in widespread use for a number of years, and find particular use for food storage purposes. While there are numerous patents issuing in the United States alone dealing with the manufacture of reclosable plastic containers and closure mechanisms therefor, the consumer of such bags is always ready for a new improved bag.
It is, therefore, desired to provide a bag or container stock material that can be impressed or embossed to form a pattern which will visually stand out to the casual observer.
It is further desired to provide a reclosable container or bag having interlocking fastening devices and a bag with a design pattern for visual enhancement providing a specific pattern when the bag is unfilled and providing another different pattern to provide a different visual effect when the bag is filled. The visual enhancement assists the user of the container in loading and unloading the container.
It is further desired to provide a process and apparatus for impressing a decorative pattern unto a plastic web stock used for making the plastic bags or containers.